Hyperventilating the hypoventilator.

A 65-year-old man had chronic hypoventilation and was demonstrated to have primary neuromuscular disease with major involvement of the thoracic bellows. By use of accessory muscles, he was able to voluntarily hyperventilate and reduce his PCO2 to normal. Hyperventilation gases must be interpreted with care in neuromuscular disease; the ability to reduce PCO2 to normal range does not exclude neuromuscular disease as a cause of chronic respiratory failure.